Mercury adsorption on gold surfaces employed in the sampling and determination of vaporous mercury: a scanning tunneling microscopy study.

To clarify the mechanism of mercury adsorption on gold surfaces thin epitaxial gold films have been exposed to trace amounts of gaseous mercury under laboratory conditions for different periods of time. The changes in the surface morphology of the thin films caused by the exposure have been studied by scanning tunneling microscopy (STM). The evolution of the surface structures with time has been also investigated, in the course of a few days after the exposure. The adsorption of mercury on the gold surfaces has caused drastic changes in the morphology of the surfaces. Pits and islands of 2 to 30 nm in diameter have appeared on the surface, their size and density per unit area depending on the amount of exposure to mercury. The formation of pits and islands followed a certain path of events.